CN203326565U - Direct current motor control circuit with heat protection function - Google Patents

Abstract

The utility model belongs to the field of direct current motor control and discloses a motor control circuit for preventing failure in a heat event in the working process of a direct current motor. In order to realize the function, the utility model adopts the technical scheme that an intelligent voltage limiting module is additionally arranged on a gate and a drain of a metal oxide semiconductor field effect transistor (MOSFET) driver of a control loop; and if the gate and the drain are short-circuited, the intelligent voltage limiting module is started to limit voltage between the gate and a source to be smaller than starting voltage, so that an MOSFET is cut off even under the working condition, the phenomenon of spontaneous combustion caused by hot stack can be effectively avoided, and the reliability and the safety of a direct current motor control circuit are ensured.

Description

A kind of DC motor control circuit with heat protection function

Technical field

The utility model belongs to the DC MOTOR CONTROL field, is specifically related to a kind of New-type electric machine control circuit for avoiding direct current machine course of work incident heat to occur.

Background technology

Along with scientific and technical development, it is more and more extensive that motor is applied in people's life, and appear at more and more in people's the vehicles, as electric bicycle, electric wheelchair, electro-tricycle even in electric automobile.Therefore, the control of motor is become to more and more important, the control effect of motor has directly determined the performance of system on the one hand, people's comfort level problem when taking these type of vehicles, and control that the more important thing is motor is determining the fail safe of this type systematic.Due to the control of motor large Current Control often, the heat therefore produced is also very many, thereby further affects the fail safe of parts and system, and this point is particularly outstanding aspect the automotive electronics series products.Many Zhou Suozhi, although the electronic technology that the automotive electronics series products is used is not forefront instantly, it must be one of instantly safe technology.The control circuit of direct current machine generally all adopts the power-type MOSFET(field effect transistor of high-side driver for security consideration) control the running of motor, due to the MOSFET(field effect transistor) not desirable switch, still there is certain impedance in it, under certain environmental condition, may occur infiltrating the situation of some addle in these motor control units, and these addle may cause circuit to produce short circuit.Such example has been arranged in actual application, and under extreme case, ECU (Electrical Control Unit) may the spontaneous combustion due to the accumulation of these heats, and finally causes whole electric system burning.Can know by analysis, this situation is the MOSFET(field effect transistor due to drive motors) short circuit of the grid leak utmost point causes.Usually, in the situation that the normal operation of ECU (Electrical Control Unit), if once above-mentioned situation occurs, because circuit for controlling motor is equipped with corresponding monitoring, so generally reminding user maintenance in time of control system, thereby can avoid causing more serious consequence.Yet, facts have proved, in some application scenario, in the situation that not operation of electronic control unit system, because the grid leak utmost point produces short circuit, motor still can obtain electric operation, owing in this kind of situation being in the situation that the primary processor of controller do not have the energising occur, system can't be carried out respective handling by reminding user naturally, if motor current value now can't cause overcurrent fuse fusing, motor is continuous service, when thermal accumlation to a certain extent the time, still can occur overheated and dieseling occurs.

Summary of the invention

The utility model is intended to the MOSFET(field effect transistor) the control voltage of field effect transistor appears automatically adjusting in the situation of short circuit in the grid leak utmost point, make this voltage be worth lower than unlatching, thereby guarantee that motor can not produce working order voluntarily, thereby avoid the generation of the event such as spontaneous combustion.The technical solution adopted in the utility model is:

A kind of DC motor control circuit with heat protection function; comprise that short-circuit resistance 1, grid drive current-limiting resistance 2, grid leak utmost point TVS protection tube 3, grid source electrode TVS protection tube 4, motor control switch 5, direct current machine 6, current-limiting fuse 7, automobile batteries 8, the grid leak utmost point of being on the scene effect pipe driver adds an intelligent voltage limiting module 9.

Described intelligent voltage limiting module comprises rectifier diode D3, NPN& PNP integrated triode Q2, PNP triode Q3, resistance R 3, resistance R 4, voltage monitoring end MON3, the PNP base stage of integrated triode Q2 is connected with PNP triode Q3 emitter, the PNP emitter of integrated triode Q2 is connected with motor control switch Q1, motor control switch Q1 is connected with direct current machine Motor, there are respectively a voltage sample point MON1 and MON2 in the front-end and back-end of Q1, diode D3, the integrated triode Q2 that NPN and PNP form, the pressure limited protection circuit that triode Q3 and current-limiting resistance R3 form, when incident heat occurs, by integrated triode Q2, triode Q3, the circuit that current-limiting resistance R3 forms can be limited to the control voltage of motor control switch Q1 the size of the junction voltage of 2 diodes, thereby reliable turn-off Q1, avoid incident heat to occur.

Useful technique effect of the present utility model is: be conducive to prevent that trouble unit from smoldering; or sealing-off appears in incident heat; the scheme implementation method is simple; and being different from heat protection method commonly used, control loop can directly carry out Reflow Soldering, and special assembly expenses does not occur; low-power consumption and voltage drop; support the DC electronic circuit, be suitable for harsh environmental condition (automobile and commercial Application), the design of environmental protection.

The accompanying drawing explanation

Fig. 1 is general DC MOTOR CONTROL loop schematic diagram.

Fig. 2 is the utility model DC MOTOR CONTROL loop schematic diagram.

Wherein 1, short-circuit resistance; 2, grid drives current-limiting resistance; 3, grid leak utmost point TVS protection tube; 4, grid source electrode TVS protection tube; 5, motor control switch; 6, direct current machine; 7, current-limiting fuse; 8, automobile batteries; 9, intelligent voltage limiting module; 10, rectifier diode D3; 11, NPN& PNP integrated triode Q2; 12, PNP triode Q3; 13, resistance R 3; 14, resistance R 4; 15, voltage monitoring end MON3.

Execution mode

Embodiment 1

Figure 1 shows that the electrical block diagram in general DC MOTOR CONTROL loop, in vehicle electronic control unit, drive circuit unit particularly, in security consideration, the high-side driver structure is used in general recommendations, and in order to guarantee energy conversion efficiency, just needs the driving voltage of high-end switch pipe will be higher than the supply voltage of input, so generally need booster circuit to realize, booster circuit output generally is designed to the twice of input voltage source.Under normal circumstances, when MRG obtains driving signal, Q1 conducting, motor operation.During if there is overcurrent condition, when the time fuse that exceeds schedule time will fuse, play the function of protection control loop.When MRG loses the driving signal, the Q1 cut-off, motor stops.But cause the short circuit of the grid leak utmost point because conducting solution infiltrates electronic control unit under some particular cases, form the path with certain resistance, as the R1 in Fig. 1 is connected across grid leak utmost point two ends, R1 is equivalent to the impedance of conducting solution, is generally a kilohm level.Voltage at grid will equal input supply voltage substantially like this, and Q1, also by conducting, still now is generally less than the overcurrent protection electric current of fuse by the electric current of motor, so motor is incited somebody to action continuous service always.As time goes on, the heat energy of Q1 will continue to assemble, and may cause product generation spontaneous combustion after temperature reaches burning-point.

Figure 2 shows that the utility model DC MOTOR CONTROL loop, the generation of the dieseling caused for fear of above-mentioned situation generation.Circuit in the dotted line frame has been added in invention.Under normal circumstances, when MRG obtains driving signal, Q2 and Q3 be in off state, Q1 conducting, motor operation.When MRG loses the driving signal, Q2 and Q3 are also in off state, and Q1 ends, and motor is stopped transport.The short circuit phenomenon caused if there is conducting solution, when MRG obtains driving signal, appearance due to short circuit phenomenon, make MRG drive signal and automobile batteries to pass through R1, D3 and R2 have formed a loop, and the collector electrode of the PNP of Q2 now and base stage have formed a diode circuit, tube voltage drop is Vd, and the voltage of MON3 will equal the D3 cathode voltage and deduct Vd like this.This voltage is inconsistent with magnitude of voltage under normal circumstances, and system can be pointed out and reports to the police and record failure mode by monitoring this voltage; When MRG loses the driving signal, Q2 and Q3 incite somebody to action the while in conducting, thereby make grid voltage by clamper, approximately only have the junction voltage size of two diodes, so switching tube will, in off state, the dieseling of foregoing description so just can not occur again.It is more than the situation of the primary processor normal operation in motor control unit.Simultaneously, even the primary processor of motor control unit does not power on, consideration is by R1, Q2, Q3, the loop that R3 forms, really act on the cut-in voltage that voltage on field effect transistor Q1 will be less than field effect transistor, motor still keeps off state, thereby avoids the circuit spontaneous combustion problem caused owing to turning round voluntarily.

Claims (1)

1. the DC motor control circuit with heat protection function; comprise that short-circuit resistance (1), grid drive current-limiting resistance (2), grid leak utmost point TVS protection tube (3), grid source electrode TVS protection tube (4), motor control switch (5), direct current machine (6), current-limiting fuse (7), automobile batteries (8); the grid leak utmost point that it is characterized in that being on the scene effect pipe driver adds an intelligent voltage limiting module (9), and the intelligent voltage limiting module comprises rectifier diode D3(10), NPN& PNP integrated triode Q2(11), PNP triode Q3(12), resistance R 3(13), resistance R 4(14), voltage monitoring end MON3(15), the PNP base stage of integrated triode Q2 is connected with PNP triode Q3 emitter, the PNP emitter of integrated triode Q2 is connected with motor control switch Q1, motor control switch Q1 is connected with direct current machine Motor, there are respectively a voltage sample point MON1 and MON2 in the front-end and back-end of Q1, diode D3, the integrated triode Q2 that NPN and PNP form, the pressure limited protection circuit that triode Q3 and current-limiting resistance R3 form, when incident heat occurs, by integrated triode Q2, triode Q3, the circuit that current-limiting resistance R3 forms is limited to the control voltage of motor control switch Q1 the size of the junction voltage of two diodes, thereby reliable turn-off Q1, avoid incident heat to occur.

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